Frame antenna arrangement



March 16, 1943. K. H. MEIER 2,314,234

FRAME ANTENNA ARRANGEMENT Filed June 1, 1940 3 Sheets-Sheet 1 12 Inventor:

Karl HQl Ytnbk QI Qf K. H. MEIER FRAME ANTENNA ARRANGEMENT March 16, 1943.

3 Sheets-Sheet 2 Filed June, 1, 1940 Inve'nfan March 16, 1943. K. H. MEIER 2,314,234

FRAME ANTENNA ARRANGEMENT Filed June 1, 194 s Sheets-Sheet 3 lyenfor: Karl flewnnck Mum Patented Mar. 1%, 1943 UNE'E'EE STATES 2,314,234 FRAME ANTENNA ARRANGEMENT Karl Heinrich Meier, Zurich, 'Switzerland, fassignor to Alfred Emil Herzer, Zurich, Switzerland Application June 1, 1940, Serial No. 338,346 In Switzerland June 26, 1939 8 Claims.

with the frame antenna the ratio of useful to disturbance voltage, which ratio is the determining factor for the quality of a radio receiving arrangement, assumes values which cannot even be approached by any of the more simple types of antennae.

If in spite of these incontestable advantages directly from the point of view of the very heavy reception disturbances, the use of frame antennae remains limited to a few particular cases. This is to be ascribed mainly to the following circumstances: firstly to their small electrical height and the consequent very small useful voltage, and further to the need to manipulate the receiving frames, that is to say, to rotate them into the direction of arrival of the transmitter to be received.

Since frame antennae, similarly to the useful antenna types, must be set up in the open air in order to obtain as much useful voltage .as possible, the rotation of the frame can only take place by means of electrical or mechanical remote control devices. It has therefore been proposed many times already to use cross frame arrangements with which the voltages received by the individual frames are brought to act upon the receiving device through a phase shifting impedance in such a way that non-directional reception is thereby made possible. With this the not inccnsiderable advantage of the directional action of the frame is certainly sacrificed. In addition certain difficulties of operation always arise from the fact that one is obliged to use resonant means in the frame antenna circuit or in the input circuit coupled thereto in order to raise the very small frame voltages to a value which takes them above the noise limit of the first amplifier tube. Particularly unfavourable are the conditions when the coupling lead between the frame antenna arrangement on the one hand and the receiving device on the other hand must be screened in order to avoid coupling between this coupling lead and neighbouring carriers of disturbance voltage. In this case moreover the matching of the receiving arrangement with a characteristic impedance of the connecting cable can be carried out practically only for one single frequency and consequently additional cable losses occur.

The invention relates to a frame antenna arrangement with non-rotatable frame antenna and two frame antennae relatively displaced by about their receiving plane. According to a feature of the inventionthe.arrangementis characterised by the fact that .the "two framevoltag'es come to act on a common'receiving circuit, that "this common receiving circuithas phase shifting means, and that the coupling ofthe fr'amevoltages to the first common receiving member takes place aperiodically.

The invention further :relates to a non-rotatable frame antenna arrangement which is constructed to be capable of being selectively switched over for directional and also for nondirectional reception. In this way it is possible to ma'kefull us'eof'th'e advantages of the rotat- 'able "frame antenna arrangement without havingto take account of the considerable disadvantages thereof.

According to a further feature of the invention,

therefore, the arrangement is characterised, by "the fact that the voltages of "the "frame antenna may be selectively conducted by means of the switching over device through at least two separate channels, that .one .of these channels has phase shifting impedances for thevolta ges of one frame, both frame voltages coming to act on a common receiving member after the phase shifting of the one frame voltage has taken place,

that the'other channel has means by'which the phase rotation of the electric currentsiis effected in sucha way that when these means are mechanically adjusted addition or subtraction of the frame voltages takes place in such a waythat a directional reception is obtained.

In contradistinction to the known constructional examples of the already mentionedcross frame arrangements for non-directional reception with'the diiferent .constructional forms of 1 the subject of the invention described in the following, connection 0f the f-rameantenna 'to the common receiving member is effected com- .pletely-aperiodically, that is to say withtheze'xception of the switching over of the frame santenna arrangement to directional tor :non-fdirec- -tional 'reception'and also the setting ofibearing or the transmitter to be received when adjusted removed. For particular cases, however, such resonant means may also be employed.

As already mentioned, it is advantageous to set the antenna arrangement up in the open air in order to obtain as much useful voltage as possible.

In this case, in order to obtain decoupling with neighbouring carriers of disturbing voltage the antenna down-lead must be screened. In addition it is certainly necessary both that the cable should be terminated in an impedance corresponding to its characteristic impedance and also that the antenna should be matched to the cable. Whilst the dimensioning of the cable transformer offers no further difficulties a useful matching of the frame to the cable isv only possible with very low inductance of the frame. One is therefore obliged to make the receiving frame with only one or at the most two turns. That the sensitivity of the antenna arrangement does not suffer by these means follows from the following consideration: if R represents the resistance in the grid circuit of the amplifier tube 5 (Fig. 1) in which resistance the received energy is consumed, and if 21 repre sents the number of turns of the primary winding of a coupling transformer, then the following relation .R'=a'z1 holds for the resistance transferred to the frame circlit.

The factor a contains the number of turns 22 of the secondary winding, assumed to be constant, the resistance R acting in the grid circuit of the tube, the degree of coupling and the like in addition.

Since the alternating voltage arising in the grid circuit; of the tube is proportional to the number of turns 2a of the frame, there is the following equation From this the energy consumed in the resistance R can be calculated to be From this equation it is seen that the energy consumed is dependent only upon the ratio of the number of turns an on the frame on the one hand and the number of turns .21 of the primary winding.

Consequently so long as the number of turns of the frame on the one hand and the number of turns of-the primary winding of the coupling transformer on the other hand are reduced in the same proportion, the same energy can be transmitted. These considerations have been clearly confirmed by experiments.

The subject of the invention is illustrated in the drawings by a number of constructional examples.

Fig. 1 is the electrical circuit diagram of a frame antenna arrangement, the cross frame ar- Figs. 3 and 3a show a constructional example other by 90.

of the bearing setting device in elevation and plan, and

Fig. 3b shows a detail thereof. Figs. 4 and 4a. show another constructional example of the same device in elevation and plan.

Fig. 5 shows a further constructional example of the subject of the invention with two possibilities of connection for directional and nondirectional reception and the coupling of the cross frame arrangement to the common receiving member.

Fig. 6 shows the electrical circuit diagram of a constructional example of the installation according to the invention with three positions of connection, that is, a first position for nondirectional reception, a second position for the usual directional reception, and a third position fo combined reception screened on one side and resulting in a cardioid pattern, with still another arrangement of the coupling and the antennae down-lead.

Figs. 7, 7a and 71) show three reception diagrams of the frame antenna arrangement according to the invention (the representation of co-ordinates has been omitted since the receiving diagram shown is generally known).

The frame antenna arrangement shown in Fig. 1 has the two frame antennae I, 2 whose reception planes are displaced relatively to one an- These frames have in one construction by way of example a diameter of cm. and have each two turns. The frame antennae are connected through a screened cable down-lead 6 by means of the input transformers 3, 4 with the common receiving device consisting of the first amplifier tube 5. The down-lead cable 6 is a screened cable consisting of three conductors I, 8, 9 and the screening sheath is connected to the common chassis potential of the receiving arrangement. The middle conductor 8 is once more surrounded by a separate screen I0 which is also connected to the common potential, this being for the purpose of decoupling the down-lead 8 from the two cable conductors I, 9. The connection of the frame I with the common receiving arrangement takes place by means of the antenna down-lead 8, 9 and the primary winding of the transformer 4, whilst frame 2 acts upon the common receiving arrangement through the conductor 1, 8 and the primary winding of the transformer 3. The secondary winding of the transformer 4 contains a resistance I l by which a phase shift of one frame voltage through is efiected. In order to effect a fixed coupling of the frame circuit to the common receiving circuit it is advantageous to employ high frequency iron transformers. The most favourable coupling data for the receiving frames given and for a down-lead having a characteristic impedance of ohms are as follows: Number of turns of primary winding 40 turns, number of turns of secondary winding 250, corresponding to 72 ,cHy and 450 ,uHy, whilst the phase displacing resistance II is of 6000 ohms. The input tube 5 may be a suitable screen grid tube or a triode, the anode resistance being 'chosen to correspond with the characteristics of the tube.

Fig. 7 shows the receiving diagram of this arrangement.

The frame antenna arrangement shown in Fig. 2 has similar frame antennae and the same dimensions as described in connection with Fig. 1. The frame circuit of this arrangement has a bearing setting device which has two cylindrical coils I2, l3 the axes of which make an angle of 90 with one another and the voltages of each frame come to act upon one of these cylindrical coils; the cylindrical coil 12 being fed from frame 1 and the cylindrical coil l3 from frame 2. Within each of these cylindrical coils is a movable coil M, 15 respectively which are arranged upon a common axis and lie in a common plane. These coils l4, are connected in series and are connected with the grid of the amplifier tube 5. The frame antennae l, 2 are once more connected through a three-conductor screened cable with the coils I2, l3.

Two constructional examples of this bearing determining coil assembly are more clearly shown in Figs. 3, 3a and 3b and 4, 4a. In the constructional form according to Figs. 3, 3a and 3b the movable coils l4, l5 are arranged within the crossed cylindrical coils l2, l3 respectively. These two coils l4, l5 are fixedly mounted upon the common axis !6. By rotating this axis the bearing of the transmitter to be received is adjusted. In order that no capacitive coupling should occur between the fixed and the movable coils these movable coils are arranged within an electrostatic screening container H. In order that this container I! should not short-circuit the coil it is cut in halves by a slit I1; this screening II is once more connected to the chassis potential and the receiver arrangement.

In the constructional form according to Figs. 4, 4a. the cylindrical coils are arranged with parallel axes and in the same plane whilst the movable coils have their axes displaced relatively to one another through 90. In order that the two cylindrical coils should not be coupled together each is mounted in a screening container ll, l8. In this constructional form also it is advisable to arrange the movable coils within an electrostatic screen. In this arrangement also the bearing of the desired transmitter is adjusted by rotating the axis IS. The reception diagram of the arrangement according to Fig. 2 is shown in Fig. '70..

With the frame antenna arrangement according to Fig. 5 the frame antennae are constructed in the same way as is described in connection with Fig. 1. The connection shown in the figure is a selectable combination of the individual arrangements shown in Figs. 1 and 2. In the position of the switches l9, 2:: shown in full lines the arrangement is connected according to Fig. 1 for non-directional reception whilst in the position of the switches 19, 20 shown in dotted lines the arrangement works with directional reception, that is according to Fig. 2. These switches I9, 20 are upon a common axis and are actuated simultaneously. Differing from the constructions according to Fig. 1 the primary and secondary windings of the input transformer 3, 4 are decoupled capacitively by the electrostatic screens 2i and 2|. These screens 2| and 2| are once more galvanically connected to the common chassis potential of the receiving arrangement.

Also in the constructional form according to Fig. 6 the frame antennae are arranged and constructed as described in connection with Fig. 1, but the individual frame voltages are fed each through a separate transformer 3, 4 to an amplifier valve 5a., 5b. The anode of each of these two tubes is connected with the switch segment of the changeover switch I911, I91), I 90. In the switch position shown in full lines, the apparatus is adjusted for non-directional reception. In

this case the mode of operation is the following-:-

The tube So. has an anode impedance '22 and delivers its amplified alternating voltages through the condenser 23 to the grid of the-tube-S. The anode of the tube 5b has also a resistance 24 as anode impedance and a phase shifting member consisting of the resistance 25, and the condenser 26. This phase shifting member effects a phase displacement of The voltages amplified by the valve 51) are therefore also impressed on the grid circuit of the common amplifier tube after they have been shifted through 90. Upon switching over the middle contact of the switches I90. and I92) and I90 and 20, the apparatus is changed over to directive reception. In this case the coils l2 and [3 of the directive or-bearing setting arrangement are connected as anode impedances, whilst the grid circuit of the tube 5 is connected to the two series connected directional coils I4, l5. These directional coils are similarl constructed to the example already referred to according to Figs. 3, 3a, 3b or 4, 4a. In the third switch position on the lowest contact of the switches 19a, I91), I90 and 2B the directive arrangement is once more connected, but simultaneously there is connected to the anode of the tube 5?) a phase shifting impedance which con sists of the condenser 21 and the resistance 28 by which the anode alternating voltage acting on the anode of the tube 51) is also impressed upon the grid circuit of the tube 5. With the last mentioned switch positions, therefore, both the voltages which correspond to the non-directional reception and also the directive voltages are active simultaneously. One has therefore here the addition of the directional reception to a nondirectional reception and thus arrives at a onesided directional reception of a so-called cardioid antenna the diagram of which is shown in Fig. 7b. This one-sided directive action is certainly efiective only for a certain position of the cross frame arrangement, but one has thereby the possibility of completely screening off a local fixed transmitter.

I claim:

1. In a frame antenna arrangement for broadcast reception, two stationary frame antennae having their reception planes disposed at right angles to each other, a common receiving memher to be acted upon by both frame voltages, a plurality of separate conducting channels, and a switch device to selectively connect said frame antennas to said separate channels, one of said channels including phase shifting ,impedances to effect phase shifting of one frame-voltage before application thereof to the common receiving member for obtaining non-directional reception, the second channel including means which are mechanically adjustable to effect addition or subtraction of the frame voltages for obtaining directional reception.

2. A frame antenna arrangement, as claimed in claim 1, in which said means in said second channel comprises two stationary cylindrical coils disposed with their axes at right angles to each other, each coil being acted upon by one of the frame voltages, and two movable coils, one in each cylindrical coil, said movable coils being arranged in a common plane on a common axis and being connected in series, said arrangement including means to apply the voltages derived from said movable coils to said common receiving member.

3. A frame antenna arrangement, as claimed in claim 1, in which said means in said second *electrical axes disposed at right angles to each other, said arrangement including means to apply the voltages derived from said movable coils to said common receiving member.

4. A frame antenna arrangement, as claimed in claim 1, including a high frequency iron coupling transformer to effect a fixed coupling.

5. A frame antenna arrangement, as claimed in claim 1, including a receiver chassis, a high frequency iron coupling transformer having a primary winding and a secondary winding, and an electrostatic screen between said windings for the purpose of capacitive decoupling, said screen being electrically connected to the chassis potential.

6. A frame antenna arrangement, as claimed in claim 1, including a receiver chassis, a high frequency iron coupling transformer having a primary winding and a secondary winding, and

,an electrostatic screen enclosing one of said windings and being electrically connected to the chassis potential.

7.YA frame antenna, as claimed in claim 1, in which said phase shifting impedances in said first channel are adapted to effect a phase shifting of 90.

8. A frame antenna arrangement, as claimed in claim 1, including a down-lead having several conductors and a screen, said screen decoupling at least one of said conductors from the remaining conductors.

KARL HEINRICH MEIER. 

